Hojun-Cho/ww
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

wcc/ww: reject a duplicate top-level main (F-D)

Browse Source 
A second top-level decl named `main` (fn/let/def/type) collides with
the entry main on the single bare `main` symbol: today both lower to a
bare `main`, w6l silently accepts the duplicate, and the program links
rc=0 then segfaults (or runs wrong), in both stages. The existing
duplicate-decl rejects key on (name, module), so a cross-module
`foo.main` vs the bare entry `main` read as distinct and slip through.

Add a program-global, name-only, cross-module uniqueness check on
`main` in the checker (both stages), colocated with the duplicate-decl
rejects and counting user decls before the -T synthesized test main.
Corpus-safe: a lone `fn main` in any package stays legal (ww has no
package-main convention -- cmatrix/lisp/mandelbrot are non-main-package
entries and keep building). This converts the silent segfault to a
loud compile error and subsumes the w6l silent-dup-main case (#31);
correct package-aware mangling of a non-entry main is deferred to the
root-unit entry-detection work (#22/#32).

Regenerates the w6c and wwdump combined.ww. Table-driven 842 test:
reject rows for let/fn/def/type main (genuine cross-module import form)
plus a negative single-main corpus-safe row that must still build+run.
This commit is contained in:
Hojun-Cho
2026-06-14 17:05:46 +09:00
parent c86c6a3bbf
commit 34c1051a63
6 changed files with 373 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
cmd/wcc/check.c
View File

@@ -2962,6 +2962,33 @@ check_file(Checker *c, Node *file)
}
c->cur_mod = NULL;
/* Program-global, name-only, cross-module uniqueness on `main`.
* `main` lowers to ONE bare entry symbol, so a second top-level
* decl named `main` (any kind, any package) collides with the
* entry at link time — today a silent segfault / link-fail in
* both stages. The (name, module) duplicate rejects above read a
* cross-package `foo.main` and the bare entry as distinct, so they
* miss this. Correct multi-main mangling (entry stays bare, the
* rest qualify) is deferred (task #32); reject loudly meanwhile
* (rule 7). Walks USER decls only — runs before the -T synth main
* is appended below — so a hosted-test build never false-counts. */
{
Node *firstmain = NULL;
for (Node *d = file->list; d; d = d->next) {
if (d->str == NULL || strcmp(d->str, "main") != 0)
continue;
if (d->kind != N_FNDECL && d->kind != N_LET
&& d->kind != N_DEF && d->kind != N_TYPEDECL)
continue;
if (firstmain == NULL) {
firstmain = d;
continue;
}
err(c, d->pos, "duplicate top-level main: only the "
"entry main may exist (task #32)");
}
}
/*
* #15 @test harness — under `w6c -T`, synthesize the entry the
* driver would otherwise hand-wire. We sit at the seam between